1. Field of the Invention
The present invention relates to a rear projection display apparatus which projects and displays video on a transmission type screen from the rear side thereof and a transmission type screen used in the rear projection display apparatus.
2. Description of the Related Art
In general, a rear projection display apparatus is configured to project and display video on a transmission type screen installed on the front face of the apparatus main body from a video projector installed on the rear side of the transmission type screen. The transmission type screen used in the rear projection display apparatus uses a lens sheet such as a lenticular lens sheet or a Fresnel lens sheet in order to obtain desired image display performance.
Such a lens sheet needs a device to maintain a predetermined planar shape since the lens sheet itself has low rigidity. In the past, the planar shape has been maintained by bonding the lens sheet to a resin molding plate or glass plate which is a rigid body.
However, because of using the resin molding or glass plate, this configuration increases the weight of the entire screen, which produces the following disadvantages: A frame retaining the screen may need increased rigidity, which tends to increase the cost of material and which increases the thickness of the frame to thereby impose restrictions on the design of the screen.
To eliminate such disadvantages, a screen configured as disclosed in e.g. Japanese Patent Laid-open No. Hei 7-92565 (Patent Document 1) has been proposed as a transmission type screen that can maintain the planar shape of a lens sheet without use of a resin molding plate or glass plate. More specifically, the screen described in Patent Document 1 is characterized by including ribs fixedly attached to at least one side of a lens sheet, brackets fixedly attached to frames disposed on the circumferential edge of the lens sheet, and an elastic body having a restoring force acting between the rib and the bracket so as to be separate from each other, and in that the lens sheet is stretched and supported by the action of the elastic body.